Currently, light sources such as light emitting diodes (LEDs) are widely used in the lighting industry, e.g., for backlighting liquid crystal displays (LCDs), street lighting, and home appliances. Direct current (DC) light sources are driven by DC power, e.g., supplied by a battery pack. Additional circuits such as transformers and converters are used to convert an alternating current (AC) electrical power to a suitable DC electrical power if an AC power source is served as the power supply.
Some light sources are driven by an AC electrical power, e.g., a light source including LED strings coupled in parallel and wired in opposite polarity connections. However, voltage variations of the AC electrical power, e.g., an AC power with a sinusoidal voltage wave, can reduce the stability of a current through the AC light source. In addition, circuits such as transformers and converters can be employed to drive the AC light sources. However, non-linear elements and energy storage elements (e.g., capacitors and inductors) contained in the transformers and converters can store energy and distort an input current of such circuits. Thus, a power factor indicative of the power efficiency may be degraded.